Modern electronic-paper designs commonly utilize colored microcapsules (typically either black or white) that migrate through a medium contained within the display when under the influence of electric fields. For example, the E-INK CORPORATION monochrome active matrix utilizes a plurality of both black and white microcapsules suspended in clear fluid within a number of hollow, spheroidal cells having transparent membranes. Thus, both the membranes of the spheroidal cells and an additional transparent electrode intervene in the space between the microcapsules and the viewer. For these and other reasons, the color white in such electronic paper displays does not look exactly like the white color of a regular sheet of paper but is instead noticeably grayer. The contrast of such electronic paper displays are also generally lower than experienced with paper.
In such existing art, microcapsules may collide with each other within the display or collide with the internal surface of the cells housing them, causing wear on the display apparatus. Image ghosting may also occur from time to time.
Another set of electronic paper displays pioneered by XEROX uses bicolor spherical electret balls (i.e. the “GYRICON” technology) suspended in a medium. This design does not use an axle as in the present invention. The GYRICON balls migrate through the medium similarly to other microcapsule based display technologies and may also collide with each other or the internal surface of their container.
Large-scale information display panels have been described that are made up of basic picture elements for application to advertising, transportation information, traffic control, news, weather, financial data and other information normally generated by computers. Such systems as described in U.S. Pat. No. 4,769,638 utilize either two intersecting planes rotational about an axis at the intersection of the planes, or 3 intersecting plane surfaces contained within two transparent holding spheres. A bar magnet acts as an armature for rotation of the element with current flow through a coil and a holding force with magnetic circuit material resists shifting from a set orientation in a two coil driven configuration. The L-shaped brackets in this type of display can lead to the loss of display elements should the display be tilted to its side or turned face down. Also, the intersecting planes, which are the display elements, allow unwanted colors and shadows to show up on each display element depending on the vertical angle of the viewer with respect to the display. This type of display has numerous components, such as a separately operable axle on each display element, and is difficult to manufacture, assemble and maintain. Materials capable of producing a magnetic shielding effect by redirecting magnetic field lines can also be saturated, and may be relatively expensive as in the case of mu-metal.